the kidney and homeostasis

• facts to learn.

  • blood enters the kidney through the rental artery.
  • blood leaves the kidney through the renal vein.
  • the ureter is a tube that carries urine from the kidney to the bladder.
  • the bladder stores urine.
  • the urethra carries urine from the bladder out of the body.
• the kidneys regulate the water content of the blood using ADH and remove products from it
• the kidneys removes urea, and excess salts and water.
• the solution of wastes in urine, and this drains from the kidneys down the ureters to the bladder, where it is stored until it can be eliminated from the body.
• process of ultrafiltration

  - there is a change in diameter of the blood vessel as it gets narrower in the capillary knot. this makes pressure in the capillary very high so that ultrafiltration can occur.

  -this means that smalls molecules like water, urea, glucose and salts are filtered under pressure through the capillary knot into the bowman's capsule.

  -big proteins and blood cells are too big to pass through the capillary knot so they stay in the blood.
• process of selective reabsorpition

  • selective reabsorpition of ALL glucose, some salts and much of the water takes place in the tubule so that the useful molecules, needed by the body go back in to the blood.
  • urine is mixture of urea, water and salt. it travels from the collecting duct to the ureter the onto the bladder where it is stored.
• kidney failure can be treated by dialysis or kidney transplant
• dialysis

  dialysis involves filtering and cleaning the blood.

  a dialysis machine uses counter current flow.

  diffusion of urea, excess salts and water occurs across the whole of the machine because it maintains a concentration gradient.
• treated by a transplant

  • tissue typing required
  • risk of rejection
  • immonsuppresent drugs must be taken
  • donor kidneys only last around 8 years
  • can be hard to find donors
  • cam lead a normal life after the operation
• treated by dialysis

  • limited diet of protein and salt.
  • regular dialysis sessions impact on the patients lifestyle.
  • available straight away.
  • expensive for the NHS
  • no immunosuppresnt drugs need to be taken